Publications

TitleAbstractYear
Filter
PMID
Filter
formalin-inactivated whole virus and recombinant subunit flavivirus vaccines.the flaviviridae is a family of arthropod-borne, enveloped, rna viruses that contain important human pathogens such as yellow fever (yf), japanese encephalitis (je), tick-borne encephalitis (tbe), west nile (wn), and the dengue (den) viruses. vaccination is the most effective means of disease prevention for these viral infections. a live-attenuated vaccine for yf, and inactivated vaccines for je and tbe have significantly reduced the incidence of disease for these viruses, while licensed vaccine ...200314714438
dna vaccines for flaviviruses. 200314714440
chimeric flaviviruses: novel vaccines against dengue fever, tick-borne encephalitis, and japanese encephalitis.many arthropod-borne flaviviruses are important human pathogens responsible for diverse illnesses, including yf, je, tbe, and dengue. live, attenuated vaccines have afforded the most effective and economical means of prevention and control, as illustrated by yf 17d and je sa14-14-2 vaccines. recent advances in recombinant dna technology have made it possible to explore a novel approach for developing live attenuated flavivirus vaccines against other flaviviruses. full-length cdna clones allow co ...200314714441
prospects for antiviral therapy. 200314714442
detection of human anti-flavivirus antibodies with a west nile virus recombinant antigen microsphere immunoassay.we report a new, suspended-microsphere diagnostic test to detect antibodies to west nile (wn) virus in human serum and cerebrospinal fluid (csf). the microsphere immunofluorescence assay can be performed in less than 3 h on specimens of <or=30 microl. a recombinant wn virus envelope (e) protein antigen is covalently coupled to fluorescent polystyrene microspheres. after incubation with diluted serum or csf, antibodies bound to the e protein antigen are detected with fluorescently labeled anti-hu ...200414715733
real-time reverse transcription loop-mediated isothermal amplification for rapid detection of west nile virus.a one-step, single tube, real-time accelerated reverse transcription loop-mediated isothermal amplification (rt-lamp) assay was developed for detecting the envelope gene of west nile (wn) virus. the rt-lamp assay is a novel method of gene amplification that amplifies nucleic acid with high specificity, efficiency, and rapidity under isothermal conditions with a set of six specially designed primers that recognize eight distinct sequences of the target. the whole procedure is very simple and rapi ...200414715762
nonsuppurative encephalitis in piglets after experimental inoculation of japanese encephalitis flavivirus isolated from pigs.nonsuppurative encephalitis was experimentally induced in 3-week-old piglets by a single intravenous inoculation of either of two strains (ib 2001 or as-6) of japanese encephalitis flavivirus (jev) isolated from field pigs. the lesions, which consisted of neuronal necrosis, neuronophagia, glial nodules, and perivas-cular cuffing, were distributed in the cerebrum, midbrain, pons, medulla oblongata, and cerebellum, particularly in the gray matter of the frontal and temporal lobes and thalamus. the ...200414715969
serologic evidence of west nile virus infection in black bears (ursus americanus) from new jersey.serum samples obtained from 51 free-ranging black bears (ursus americanus) in northwestern new jersey in february and march 2002 were analyzed for neutralizing antibodies to west nile virus (wnv) and st. louis encephalitis virus. three (6%) of the black bears tested positive for wnv-neutralizing antibodies. one additional sample was positive for flavivirus-neutralizing antibodies but could not be differentiated for a specific virus type. this is the first report of wnv infection in black bears.200314733286
serologic evidence of west nile virus infection in birds, tamaulipas state, méxico.following the introduction of west nile virus (wnv) into north america in 1999, surveillance for wnv in migratory and resident birds was established in tamaulipas state, northern méxico in december 2001. overall, 796 birds representing 70 species and 10 orders were captured and assayed for antibodies to wnv. nine birds had flavivirus-specific antibodies by epitope-blocking enzyme-linked immunosorbent assay; four were confirmed to have antibody to wnv by plaque reduction neutralization test. the ...200314733673
structure of the dengue virus envelope protein after membrane fusion.dengue virus enters a host cell when the viral envelope glycoprotein, e, binds to a receptor and responds by conformational rearrangement to the reduced ph of an endosome. the conformational change induces fusion of viral and host-cell membranes. a three-dimensional structure of the soluble e ectodomain (se) in its trimeric, postfusion state reveals striking differences from the dimeric, prefusion form. the elongated trimer bears three 'fusion loops' at one end, to insert into the host-cell memb ...200414737159
genetic vaccination of mice with plasmids encoding the ns1 non-structural protein from tick-borne encephalitis virus and dengue 2 virus.although there is a safe, inexpensive and efficacious vaccine against yellow fever, vaccination against other flavivirus diseases is less successful. there is no licensed vaccine against dengue fever and current vaccines against tick-borne encephalitis (tbe) and japanese encephalitis are expensive and require several injections. furthermore novel vaccines containing only virus envelope proteins may raise fears over antibody mediated enhancement (ade) of disease. here we report the successful use ...200414739654
vaccination of human volunteers with monovalent and tetravalent live-attenuated dengue vaccine candidates.four serotypes of monovalent live attenuated dengue virus vaccine candidates were tested for reactogenicity and immunogenicity in 49 flavivirus non-immune adult human volunteers. the four monovalent candidates were then combined into a tetravalent formulation and given to another 10 volunteers. neutralizing antibody seroconversion rates after a single-dose monovalent vaccination ranged from 53% to 100%. solicited reactogenicity was scored by each volunteer. a composite index, the reactogenicity ...200314740952
atypical antibody responses in dengue vaccine recipients.eight of 69 (12%) healthy adult volunteers vaccinated with monovalent live-attenuated dengue virus (denv) vaccine candidates had atypical antibody responses, with depressed igm:igg antibody ratios and induction of high-titer hemagglutination-inhibiting and neutralizing (nt) antibodies to all four denv serotypes. these features suggested flavivirus exposure prior to denv vaccination, yet no volunteer had a history of previous flavivirus infection, flavivirus vaccination, or antibody to flavivirus ...200314740953
phase i trial of 16 formulations of a tetravalent live-attenuated dengue vaccine.laboratory-attenuated strains of each of the four dengue serotypes previously tested as monovalent vaccines in volunteers were combined and tested for immunogenicity, safety, and reactogenicity in 16 dosage combinations. tetravalent vaccines made using combinations of high (10(5-6) plaque-forming units [pfu]/dose) or low (10(3.5-4.5) pfu/dose) dosage formulations of each of the four viruses were inoculated in 64 flavivirus non-immune adult volunteers to determine which, if any, formulation raise ...200314740955
development of a gb virus b marmoset model and its validation with a novel series of hepatitis c virus ns3 protease inhibitors.gb virus b (gbv-b), a flavivirus closely related to hcv, has previously been shown to infect and replicate to high titers in tamarins (saguinus sp.). this study describes the use of gbv-b infection and replication in the common marmoset (callithrix jacchus) for the successful development and validation of a surrogate animal model for hepatitis c virus (hcv). infection of marmosets with gbv-b produced a viremia that peaked at 10(8) to 10(9) genome copies/ml for a period of 40 to 60 days followed ...200414747571
phylogenetic analysis of bovine viral diarrhea viruses using five different genetic regions.phylogenetic analysis of the five different regions (5' non-coding region (5'ncr), n(pro), e2, ns3 and ns5b-3'ncr) of 48 japanese and reported bovine viral diarrhea virus (bvdv) genomes was performed. japanese bvdvs were segregated into bvdv1 subdivided into six subgroups and bvdv2. one isolate, so cp/75, isolated in 1975 and previously proposed as subgroup 1e according to its 5'ncr sequence, was quite unique and formed an independent lineage in the tree of any region. another isolate, 190cp, ob ...200414749175
fatal west nile virus encephalitis in a renal transplant recipient.west nile virus (wnv), a mosquito-transmitted single-stranded rna flavivirus, causes human disease of variable severity. we report clinical and pathologic findings of fatal encephalitis from the transmission of wnv from an organ donor to a kidney transplant recipient. the patient developed a febrile illness 18 days after transplantation, which progressed to encephalitis. postmortem examination demonstrated extensive viral encephalopathic changes. immunohistochemical studies highlighted wnv antig ...200414750237
activation of virus-specific memory b cells in the absence of t cell help.humoral immunity is maintained by long-lived plasma cells, constitutively secreting antibodies, and nonsecreting resting memory b cells that are rapidly reactivated upon antigen encounter. the activation requirements for resting memory b cells, particularly the role of t helper cells, are unclear. to analyze the activation of memory b cells, mice were immunized with human cytomegalovirus, a complex human herpesvirus, and tick-born encephalitis virus, and a simple flavivirus. b cell populations d ...200414769849
cell-mediated immune responses in healthy children with a history of subclinical infection with japanese encephalitis virus: analysis of cd4+ and cd8+ t cell target specificities by intracellular delivery of viral proteins using the human immunodeficiency virus tat protein transduction domain.japanese encephalitis virus (jev), a single-stranded positive-sense rna virus of the family flaviviridae, is the major cause of paediatric encephalitis in asia. the high incidence of subclinical infections in japanese encephalitis-endemic areas and subsequent evasion of encephalitis points to the development of immune responses against jev. humoral responses play a central role in protection against jev; however, cell-mediated immune responses contributing to this end are not fully understood. t ...200414769905
mimicking live flavivirus immunization with a noninfectious rna vaccine.flaviviruses are human pathogens of world-wide medical importance. they have recently received much additional attention because of their spread to new regions (such as west nile virus to north america), highlighting their potential as newly emerging disease agents. using tick-borne encephalitis virus, we have developed and evaluated in mice a new genetic vaccine based on self-replicating but noninfectious rna. this rna contains all of the necessary genetic information for establishing its repli ...200414769933
safety and immunogenicity of a three dose regimen of two tetravalent live-attenuated dengue vaccines in five- to twelve-year-old thai children.the safety and immunogenicity of tetravalent live-attenuated dengue vaccines after a three dose vaccination series were evaluated in thai children.200414872173
alterations of pr-m cleavage and virus export in pr-m junction chimeric dengue viruses.during the export of flavivirus particles through the secretory pathway, a viral envelope glycoprotein, prm, is cleaved by the proprotein convertase furin; this cleavage is required for the subsequent rearrangement of receptor-binding e glycoprotein and for virus infectivity. similar to many furin substrates, prm in vector-borne flaviviruses contains basic residues at positions p1, p2, and p4 proximal to the cleavage site; in addition, a number of charged residues are found at position p3 and be ...200414963133
contribution of disulfide bridging to epitope expression of the dengue type 2 virus envelope glycoprotein.the individual contributions of each of the six conserved disulfide (ss) bonds in the dengue 2 virus envelope (e) glycoprotein (strain 16681) to epitope expression was determined by measuring the reactivities of a panel of well-defined monoclonal antibodies (mabs) with llc-mk(2) cells that had been transiently transformed with plasmid vectors expressing e proteins that were mutant in their ss bonds. three domain i (di) epitopes (c1, c3, and c4) were affected by elimination of any ss bond and wer ...200414963174
structure of a flavivirus envelope glycoprotein in its low-ph-induced membrane fusion conformation.enveloped viruses enter cells via a membrane fusion reaction driven by conformational changes of specific viral envelope proteins. we report here the structure of the ectodomain of the tick-borne encephalitis virus envelope glycoprotein, e, a prototypical class ii fusion protein, in its trimeric low-ph-induced conformation. we show that, in the conformational transition, the three domains of the neutral-ph form are maintained but their relative orientation is altered. similar to the postfusion c ...200414963486
impaired t helper 1 function of nonstructural protein 3-specific t cells in japanese patients with encephalitis with neurological sequelae.japanese encephalitis virus (jev) is the principal cause of viral encephalitis. the predominance of children among patients with encephalitis in areas where jev is endemic that do not have immunization programs suggests that acquired immunity is critical in protecting adults against symptomatic jev encephalitis. we characterized and compared the t cell response to nonstructural (ns) protein 3 between healthy individuals naturally exposed to jev and patients in the convalescent phase of jev encep ...200414976606
recombinant kunjin virus replicon vaccines induce protective t-cell immunity against human papillomavirus 16 e7-expressing tumour.the persistence of the e7 oncoprotein in transformed cells in human papillomavirus (hpv)-associated cervical cancer provides a tumour-specific antigen to which immunotherapeutic strategies may be directed. self-replicating rna (replicon) vaccine vectors derived from the flavivirus kunjin (kun) have recently been reported to induce t-cell immunity. here, we report that inclusion of a ctl epitope of hpv16 e7 protein into a polyepitope encoded by a kun vector induced e7-directed t-cell responses an ...200414980484
determination of the disulfide bond arrangement of dengue virus ns1 protein.the 12 half-cystines of ns1 proteins are absolutely conserved among flaviviruses, suggesting their importance to the structure and function of these proteins. in the present study, peptides from recombinant dengue-2 virus ns1 were produced by tryptic digestion in 100% h(2)(16)o, peptic digestion in 50% h(2)(18)o, thermolytic digestion in 50% h(2)(18)o, or combinations of these digestion conditions. peptides were separated by size exclusion and/or reverse phase high performance liquid chromatogra ...200414981082
interim guidelines for the evaluation of infants born to mothers infected with west nile virus during pregnancy.west nile virus (wnv) is a single-stranded rna flavivirus with antigenic similarities to japanese encephalitis and st. louis encephalitis viruses. it is transmitted to humans primarily through the bites of infected mosquitoes. flavivirus infection during pregnancy has been associated rarely with both spontaneous abortion and neonatal illness but has not been known to cause birth defects in humans. during 2002, a total of 4,156 cases of wnv illness in humans, including 2,946 cases of neuroinvasiv ...200414985654
west nile virus: an overview of its spread in europe and the mediterranean basin in contrast to its spread in the americas.west nile (wn) virus is a mosquito-transmitted flavivirus. it is widely distributed in africa, the middle east, asia, and southern europe and was recently introduced to north america. birds are involved in the cycle of transmission as amplifying hosts. humans and horses are considered accidental dead-end hosts. wn fever was initially considered a minor arbovirosis, usually inducing a nonsymptomatic or a mild flu-like illness in humans, but some cases of encephalitis associated with fatalities we ...200414986160
characterization of a membrane-associated trimeric low-ph-induced form of the class ii viral fusion protein e from tick-borne encephalitis virus and its crystallization.the interaction of a dimeric membrane anchor-free form of the envelope protein e (se dimer) from tick-borne encephalitis virus with liposomes at acidic ph levels leads to its conversion into membrane-inserted se trimers. electron microscopy shows that these trimers have their long dimensions along the threefold molecular axis, which is oriented perpendicularly to the plane of the membrane, where the protein inserts via the internal fusion peptide. liposomes containing se at their surface display ...200414990739
virus spread, tissue inflammation and antiviral response in brains of flavivirus susceptible and resistant mice acutely infected with murray valley encephalitis virus.inborn resistance to flaviviruses, conferred by a single chromosome 5 locus flv, is a genetic trait operative in wild mice and a few strains of laboratory mice. in this study we have used in situ hybridisation to trace the spread of flavivirus genomic rna within the brains of flavivirus susceptible c3h/hejarc and congenic resistant c3h.pri- flv(r) mice following infection with murray valley encephalitis virus (mve) in parallel to studying a brain histopathology and induction of cellular genes in ...200414991436
solution structure of dengue virus capsid protein reveals another fold.dengue virus is responsible for approximately 50-100 million infections, resulting in nearly 24,000 deaths annually. the capsid (c) protein of dengue virus is essential for specific encapsidation of the rna genome, but little structural information on the c protein is available. we report the solution structure of the 200-residue homodimer of dengue 2 c protein. the structure provides, to our knowledge, the first 3d picture of a flavivirus c protein and identifies a fold that includes a large di ...200414993605
suramin inhibits the in vitro expression of encephalitis b virus proteins ns3 and e.in this study, the mechanism by which suramin inhibits the replication of epidemic encephalitis b virus was explored to provide a theoretical basis for its further application in clinical practice. after viral infection of hepg2 and imr-32 cells, different concentrations of suramin were added to the culture media, and then the cultural supernatants and infected cells were collected 48 h later. for the evaluation of the curative effect, cytopathic effect (cpe), virus titers, the expression of vir ...200315015640
purification and crystallization reveal two types of interactions of the fusion protein homotrimer of semliki forest virus.the fusion proteins of the alphaviruses and flaviviruses have a similar native structure and convert to a highly stable homotrimer conformation during the fusion of the viral and target membranes. the properties of the alpha- and flavivirus fusion proteins distinguish them from the class i viral fusion proteins, such as influenza virus hemagglutinin, and establish them as the first members of the class ii fusion proteins. understanding how this new class carries out membrane fusion will require ...200415016874
longitudinal studies of west nile virus infection in avians, yucatán state, méxico.following the introduction of west nile virus (wnv) into north america in 1999, surveillance for evidence of infection with this virus in migratory and resident birds was established in yucatán state, méxico in march 2000. overall, 8611 birds representing 182 species and 14 orders were captured and assayed for antibodies to wnv. of these, 5066 (59%) birds were residents and 3545 (41%) birds were migrants. twenty-one (0.24%) birds exhibited evidence of flavivirus infection. of these, 8 birds had ...200415018768
detection of australasian flavivirus encephalitic viruses using rapid fluorogenic taqman rt-pcr assays.the development of single, sensitive, fluorogenic reverse transcriptase-polymerase chain reaction (taqman) assays were required for the rapid and specific detection of three encephalitic viruses found in the australasian region, namely; japanese encephalitis virus (jev), murray valley encephalitis virus (mvev), and kunjin virus (kunv). primers and a fluorogenic probe were individually designed to be complementary to a nucleotide region encompassing the 3' terminus of the nonstructural (ns) 5 gen ...200415041213
myristoylation of viral and bacterial proteins. 200415051068
recent advancement in flavivirus vaccine development.lately, the magnitude of cumulative diseases burden caused by flaviviruses, such as dengue virus, japanese encephalitis virus, tick-borne encephalitis virus, west nile virus and yellow fever virus, has reached an unprecedented level with the sizes of human and animal populations at risk increasing sharply. these diseases present highly complex medical, economic and ecologic problems, some effecting primarily human and others affecting human, livestock and wildlife. the large body of recent publi ...200415056045
exocytosis and fas mediated cytolytic mechanisms exert protection from west nile virus induced encephalitis in mice.infection of mice with the flaviviruses west nile virus (wnv) and murray valley encephalitis (mve) induces cytolytic t-cell responses which are highly cross-reactive on target cells infected with heterologous flaviviruses. of c57bl/6 mice infected with low doses (10(2)-10(6) pfu) of either virus, 30-40% develop encephalitis and die within 10-12 days. mice with defects in the fas or granule exocytosis (perforin and granzymes a and b) pathway of cellular cytotoxicity display reduced mortality and ...200415061770
routes of inoculation and the immune response to a resolving genital flavivirus infection in a novel murine model.the prolonged, abnormal immune response patterns produced by many sexually transmitted viruses have been intensively studied. because normal antiviral immune responses in the vagina are less well-defined, we developed a resolving murine model using vaginal inoculation with the flavivirus, west nile virus. infection resulted in 12% mortality, with sterile protective immunity to vaginal or systemic re-challenge. b-cell numbers increased in the vaginal mucosa from day 1-7 after primary infection, w ...200415061771
evidence that a mechanism for efficient flavivirus budding upregulates mhc class i.an appealing hypothesis for the biological role of flavivirus-induced, interferon-independent, upregulation of mhc class i on the surface of infected cells is that of viral immune evasion from nk cell recognition. here we show that a mechanism for efficient flavivirus morphogenesis interferes with the mhc class i pathway, using a flavivirus budding mutant and recombinant expression of wild-type and mutant forms of the flavivirus structural proteins. we propose that the phenomenon of flavivirus-m ...200415061772
rna interference, arthropod-borne viruses, and mosquitoes.rna interference (rnai) probably functions as an antiviral mechanism in most eukaryotic organisms. variations in the activity of this antiviral pathway in mosquitoes could explain, in part, why some mosquitoes are competent vectors of medically important, arthropod-borne viruses (arboviruses) and others are not. there are three lines of evidence that show the rnai pathway exists in aedes species that transmit arboviruses. the first is that recombinant sindbis viruses expressing a rna fragment fr ...200415068882
west nile virus: pathogenesis and therapeutic options.west nile virus, a member of the family flaviviridae, has spread throughout the united states. with more than 9000 cases and 200 deaths in 2003, west nile virus has become the most common cause of viral encephalitis in several states. west nile virus encephalitis is a zoonosis. the life cycle of the virus includes mainly birds as hosts and mosquitoes as vectors. humans are accidental hosts, insufficient to support the life cycle of the virus because of low-grade, transient viremia. however, huma ...200415068983
functional and structural similarities between the internal ribosome entry sites of hepatitis c virus and porcine teschovirus, a picornavirus.initiation of protein synthesis on picornavirus rna requires an internal ribosome entry site (ires). typically, picornavirus ires elements contain about 450 nucleotides (nt) and use most of the cellular translation initiation factors. however, it is now shown that just 280 nt of the porcine teschovirus type 1 talfan (ptv-1) 5' untranslated region direct the efficient internal initiation of translation in vitro and within cells. in toeprinting assays, assembly of 48s preinitiation complexes from ...200415078929
la protein binds to ns5 and ns3 and to the 5' and 3' ends of dengue 4 virus rna.in vitro replication of dengue virus requires the presence of cis-acting elements within the 5' end and the 3' utr of the viral genome. some, like the putative cyclization sites (pcs), may promote interaction at both ends of the viral genome. to investigate whether viral or cellular proteins could be involved in this interaction, uv-induced cross-linking assays using extracts from the monocytic cell line u937 were performed. our data demonstrate that the 5' end and the 3' utr with the pcs intera ...200415084396
the non-structural 3 (ns3) protein of dengue virus type 2 interacts with human nuclear receptor binding protein and is associated with alterations in membrane structure.flaviviral infections produce a distinct array of virus-induced intracellular membrane alterations that are associated with the flaviviral replication machinery. currently, it is still unknown which flaviviral protein(s) is/are responsible for this induction. using yeast two-hybrid and co-immunoprecipitation analyses, we demonstrated that the ns3 protein of dengue virus type 2 interacted specifically with nuclear receptor binding protein (nrbp), a host cellular protein that influences traffickin ...200415084397
spinal cord neuropathology in human west nile virus infection.during the 1999 new york city west nile virus (wnv) outbreak, 4 patients with profound muscle weakness, attributed to guillain-barré syndrome, were autopsied. these cases were the first deaths caused by wnv, a flavivirus, to be reported in the united states. the patients' brains had signs of mild viral encephalitis; spinal cords were not examined. during the 2002 national epidemic, several patients in mississippi had acute flaccid paralysis. electrophysiologic studies localized the lesions to th ...200415086282
viral vaccine meeting held in barcelona, october 25-28, 2003. 200415098545
conserved rna secondary structures in flaviviridae genomes.presented here is a comprehensive computational survey of evolutionarily conserved secondary structure motifs in the genomic rnas of the family flaviviridae: this virus family consists of the three genera flavivirus, pestivirus and hepacivirus and the group of gb virus c/hepatitis g virus with a currently uncertain taxonomic classification. based on the control of replication and translation, two subgroups were considered separately: the genus flavivirus, with its type i cap structure at the 5' ...200415105528
conserved amino acids 193-324 of non-structural protein 3 are a dominant source of peptide determinants for cd4+ and cd8+ t cells in a healthy japanese encephalitis virus-endemic cohort.our earlier identification of the non-structural protein 3 (ns3) of japanese encephalitis virus (jev) as a dominant cd4+ as well as cd8+ t cell-eliciting antigen in a healthy jev-endemic cohort with a wide hla distribution implied the presence of several epitopes dispersed over the length of the protein. use of various truncated versions of ns3 in lymphocyte stimulation and interferon (ifn)-gamma secretion assays revealed that amino acids (aa) 193-324 of ns3 were comparable with, if not superior ...200415105530
accumulation of a 3'-terminal genome fragment in japanese encephalitis virus-infected mammalian and mosquito cells.japanese encephalitis virus (jev) contains a single positive-strand rna genome nearly 11 kb in length and is not formally thought to generate subgenomic rna molecules during replication. here, we report the abundant accumulation of a 3'-terminal 521- to 523-nucleotide (nt) genome fragment, representing a major portion of the 585-nt 3' untranslated region, in both mammalian (bhk-21) and mosquito (c6/36) cells infected with any of nine strains of jev. in bhk-21 cells, the viral genome was detected ...200415113895
ns2a-ns2b sequence analysis of den-4 virus strains.to study the genetic variability of den-4 chinese isolates, and to trace the origin of dv4 chinese isolates, we cloned and sequenced the ns2a-ns2b junction of 5 isolates and prototype dv4 (h-241). our results show that isolates from the 1990 guangdong epidemic, which were isolated in the early, middle, and late periods of the epidemic, share the same sequence in the ns2a-ns2b junction. the sequence similarity between isolates from the guangdong epidemic in 1990 and dv4 h-241 is 96%; these isolat ...200315115127
molecular determinants of virulence of west nile virus in north america.west nile virus (wnv) is a mosquito-borne flavivirus that until very recently had not been found in the americas. in 1999, there was an outbreak of west nile encephalitis in new york and surrounding areas, involving 62 human cases, including 7 fatalities. the virus has subsequently become established in the united states of america (u.s.) with 4156 human cases, including 284 deaths, in 2002. the wnv strains found in the u.s. are members of "lineage i", a genetic grouping that includes viruses fr ...200415119761
evolution and dispersal of encephalitic flaviviruses.there are two major groups of encephalitic flaviviruses, those that infect and are transmitted by ticks, particularly ixodes spp. and those that infect and are transmitted by mosquitoes, particularly culex spp. the tick-borne encephalitic flaviviruses exhibit evolutionary characteristics that are largely determined by the protracted life cycle of the tick, its habitat and the prevailing climatic conditions. these viruses appear to have evolved gradually from non-encephalitic viruses that radiate ...200415119763
the entry machinery of flaviviruses.we have been using the flavivirus tick-borne encephalitis virus (tbev) as a model system for investigating the molecular mechanisms underlying the membrane fusion process mediated by a class ii viral fusion protein, the flavivirus envelope protein e. in the mature virion this protein exists as a metastable dimer that dissociates at the acidic ph in endosomes and is converted into a more stable trimeric conformation. the dimer dissociation step liberates an internal fusion peptide that interacts ...200415119768
neurovirulence and host factors in flavivirus encephalitis--evidence from clinical epidemiology.japanese encephalitis virus (jev) and west nile virus (wnv) provide some of the most important examples of emerging zoonotic viral encephalitides. for these flaviviruses, only a small proportion of those infected develop clinical features, and these may range from a non-specific flu-like illness to a severe fatal meningoencephalitis, often with parkinsonian features, or a poliomyelitis-like flaccid paralysis. the factors governing the clinical presentations, and outcome of flavivirus infections ...200415119771
a novel principle of attenuation for the development of new generation live flavivirus vaccines.the genus flavivirus includes a number of important human pathogens that impose major health problems in large regions of the world. the emergence of flaviviruses in new geographic regions (e.g., west nile virus in north america) and rapid socioeconomic changed in many developing countries where flaviviruses such as dengue virus and japanese encephalitis virus and endemic demand the development of new vaccines against these diseases. using tick-borne encephalitis virus as a model we have establi ...200415119774
serosurveillance for japanese encephalitis in children in several districts of west bengal, india.to evaluate the prevalence of antibodies to flaviviruses, particularly japanese encephalitis (je) in children.200415124845
hepatitis c virus glycoprotein e2 contains a membrane-proximal heptad repeat sequence that is essential for e1e2 glycoprotein heterodimerization and viral entry.the e1 and e2 glycoproteins of hepatitis c virus form a noncovalently associated heterodimer that mediates viral entry. glycoprotein e2 comprises a receptor-binding domain (residues 384-661) that is connected to the transmembrane domain (residues 716-746) via a highly conserved sequence containing a hydrophobic heptad repeat (residues 675-699). alanine- and proline-scanning mutagenesis of the e2 heptad repeat revealed that leu675, ser678, leu689, and leu692 are important for e1e2 heterodimerizat ...200415136562
[west nile virus. an unusual flavivirus with increased importance]. 200415137587
clinical and neuroradiologic features of 39 consecutive cases of west nile virus meningoencephalitis.west nile virus (wnv) is a flavivirus wnv that has spread westwards across north america in recent years. it can cause a febrile illness and infection of the central nervous system, which is associated with poor outcome.200415140603
virus inactivation by nucleic acid extraction reagents.many assume that common methods to extract viral nucleic acids are able to render a sample non-infectious. it may be that inactivation of infectious virus is incomplete during viral nucleic acid extraction methods. accordingly, two common viral nucleic acid extraction techniques were evaluated for the ability to inactivate high viral titer specimens. in particular, the potential for trizol ls reagent (invitrogen corp., carlsbad, ca) and avl buffer (qiagen, valencia, ca) were examined to render s ...200415158603
[molecular typing of the tick-borne encephalitis virus isolated from patients with different-infection severities in the south of russia's far east].the thick-borne encephalitis virus (tbev), which is widespread in the eurasian continent, belongs to the flaviviridae family, flavirus genus, and comprises the far eastern, siberian and west european subtypes. it was for the first time that the gene part of the e 24 strain envelope glycoprotein of tbev, which caused infection in residents of the south of russia's far east, was analyzed. it was established that the tbev far-eastern subtype causes different-severity disease cases ranging from the ...200415164719
molecular determinants of antigenicity of two subtypes of the tick-borne flavivirus omsk haemorrhagic fever virus.in 1964, d. h. clarke defined two antigenic subtypes of omsk haemorrhagic fever virus (ohfv) based on polyclonal antibody absorption and haemagglutination assays. the current report defines the molecular basis for these antigenic subtypes by comparison of the complete genomes of ohfv strains kubrin (subtype i) and bogoluvovska (subtype ii). there were six nucleotide differences between these two strains throughout the entire genome and they encoded four amino acid changes including three in the ...200415166446
methylene blue photoinactivation of rna viruses.we present a review of the current status of the use of methylene blue (mb) photoinactivation of viruses starting with the first early observations up to its current use to inactivate hiv-1 in blood products. basic mechanism of action studies conducted with model bacteriophages indicate that mb-photomediated viral rna-protein crosslinkage is a primary lesion and that oxygen, specifically singlet oxygen, is very important also. basic studies on the mechanism of action with hiv are lacking; howeve ...200415168794
flaviviruses and apoptosis regulation. 200415171612
dengue virus serotyping based on envelope and membrane and nonstructural protein ns1 serotype-specific capture immunoglobulin m enzyme-linked immunosorbent assays.envelope and membrane (e/m) and nonstructural protein ns1 serotype-specific capture immunoglobulin m (igm) enzyme-linked immunosorbent assays (elisas) were developed to differentiate four dengue virus serotypes. a total of 93 anti-dengue virus igm-positive serum samples collected between days 5 and 45 of illness from 59 confirmed dengue patients were analyzed. the results showed that positive serotype specificity could be identified for 86.1 and 47.6% of serum samples tested for e/m-specific igm ...200415184425
[circulation of west nile virus (flaviviridae, flavivirus) and some other arboviruses in the ecosystems of volga delta, volga-akhtuba flood-lands and adjoining arid regions (2000-2002)].comprehensive virological, serological as well as genetic studies of the ecology of west nile virus (wnv) as well as of some other arboviruses were undertaken in different ecosystems in the territories of the astrakhan region and of the kalmyk republic. the main carriers (mosquitoes, ticks, birds and mammals) were defined as involved in the circulation of viruses within the natural and anthropogenic biocenosis. phylogenetic examinations of isolated strains and samples, which were positive in rt- ...200415188655
encephalomyelitis from west nile flavivirus in 3 alpacas. 200415188827
solution structure and antibody binding studies of the envelope protein domain iii from the new york strain of west nile virus.the solution structure of domain iii from the new york west nile virus strain 385-99 (wn-red3) has been determined by nmr methods. the west nile domain iii structure is a beta-barrel structure formed from seven anti-parallel beta-strands in two beta-sheets. one anti-parallel beta-sheet consists of beta-strands beta1 (phe(299)-asp(307)), beta2 (val(313)-tyr(319)), beta4 (arg(354)-leu(355)), and beta5 (lys(370)-glu(376)) arranged so that beta2 is flanked on either side by beta1 and beta5. the shor ...200415190071
[tick-borne human pathogenic microorganisms found in europe and those considered nonpathogenic. part i: ticks and viruses].the importance of tick-borne encephalitis (tbe) and lyme borreliosis-the main european tick-borne diseases-is steadily growing. this fact is due to many different factors including climate changes. however, across europe many other human pathogenic viruses, bacteria, and parasites are found in ticks. this article gives an overview of tick-borne human pathogenic viruses present in europe as well as those considered nonpathogenic. it also deals with the various species of vector-competent ticks. a ...200415205783
yellow fever outbreak, imatong, southern sudan.in may 2003, the world health organization received reports about a possible outbreak of a hemorrhagic disease of unknown cause in the imatong mountains of southern sudan. laboratory investigations were conducted on 28 serum samples collected from patients in the imatong region. serum samples from 13 patients were positive for immunoglobulin m antibody to flavivirus, and serum samples from 5 patients were positive by reverse transcription-polymerase chain reaction with both the genus flavivirus- ...200415207058
regulation of antigen processing and presentation molecules in west nile virus-infected human skin fibroblasts.infection of humans with the west nile flavivirus principally occurs via tick and mosquito bites. here, we document the expression of antigen processing and presentation molecules in west nile virus (wnv)-infected human skin fibroblast (hff) cells. using a new flavivirus-specific antibody, 4g4, we have analyzed cell surface human leukocyte antigen (hla) expression on virus-infected cells at a single cell level. using this approach, we show that west nile virus infection alters surface hla expres ...200415207616
live flavivirus vaccines: reasons for caution.context: dengue, japanese encephalitis, tick-borne encephalitis, yellow fever, and west nile viruses cause substantial morbidity and mortality each year. modern transportation and the relaxation of mosquito-control measures are largely responsible for the increase of disease caused by flaviviruses. without effective antiviral drugs, vaccination offers the best chance of decreasing the incidence of these diseases, and live virus vaccines are the most promising and cost effective. however, flavivi ...200415207960
stiff-person syndrome following west nile fever.stiff-person syndrome is a rare autoimmune disorder associated with antibodies against glutamic acid decarboxylase (gad), the key enzyme in gamma-aminobutyric acid synthesis. in most cases, a trigger cannot be identified.200415210535
sequences of flavivirus-related rna viruses persist in dna form integrated in the genome of aedes spp. mosquitoes.flavivirus-related sequences have been discovered in the dsdna genome of aedes albopictus and aedes aegypti mosquitoes, demonstrating for the first time an integration into a eukaryotic genome of a multigenic sequence from an rna virus that replicates without a recognized dna intermediate. in the aedes albopictus c6/36 cell line, an open reading frame (orf) of 1557 aa with protease/helicase and polyprotein processing domains characteristic of flaviviruses was identified. it is closely related to ...200415218182
exchanging the yellow fever virus envelope proteins with modoc virus prm and e proteins results in a chimeric virus that is neuroinvasive in scid mice.a chimeric flavivirus infectious cdna was constructed by exchanging the premembrane (prm) and envelope (e) genes of the yellow fever virus vaccine strain 17d (yf17d) with the corresponding genes of modoc virus (mod). this latter virus belongs to the cluster of the "not-known vector" flaviviruses and is, unlike yf17d, neuroinvasive in scid mice. replication of in vitro-transcribed rna from this chimeric flavivirus was shown by [(3)h]uridine labeling and rna analysis. expression of the mod prm and ...200415220415
west nile: worldwide current situation in animals and humans.west nile (wn) virus is a mosquito-borne flavivirus that is native to africa, europe, and western asia. it mainly circulates among birds, but can infect many species of mammals, as well as amphibians and reptiles. epidemics can occur in rural as well as urban areas. transmission of wn virus, sometimes involving significant mortality in humans and horses, has been documented at erratic intervals in many countries, but never in the new world until it appeared in new york city in 1999. during the n ...200415225984
distribution of e and ns1 proteins of tbe virus in mammalian and tick cells.four monoclonal antibodies recognizing tbev proteins were prepared. three of them (2/h6, 8/a10, 5/f9) specifically recognize the structural e protein and the fourth binds to the nonstructural ns1 protein. these antibodies were used for an immunofluorescence study of tbev protein distribution in infected mammalian host and tick vector tissue culture cells. any differences in the distribution of the e and ns1 proteins were revealed. in porcine ps cell line the proteins were localized in the cytopl ...200415227801
west nile virus infection of horses.west nile virus (wnv) is a flavivirus closely related to japanese encephalitis and st. louis encephalitis viruses that is primarily maintained in nature by transmission cycles between mosquitoes and birds. occasionally, wnv infects and causes disease in other vertebrates, including humans and horses. west nile virus has re-emerged as an important pathogen as several recent outbreaks of encephalomyelitis have been reported from different parts of europe in addition to the large epidemic that has ...200415236677
backbone and side chain resonance assignments of domain iii of the tick-borne langat flavivirus envelope protein. 200415243186
tick-borne encephalitis in childhood--consensus 2004.tick-borne encephalitis (tbe) is a communicable disease caused by a flavi-virus, ticks being the main vectors. the nervous system is affected, four clinical features of different severity are observed: meningitis, meningoencephalitis, meningoencephalomyelitis, meningoradiculoneuritis. tbe is a preventable disease, which is rapidly becoming a growing public health problem in europe. so far no causal treatment is possible but an efficient, safe vaccination is available. during the 6th meeting of t ...200415244050
solution structure and structural dynamics of envelope protein domain iii of mosquito- and tick-borne flaviviruses.the mosquito-borne west nile (wnv) and dengue 2 (den2v) viruses and tick-borne langat (lgtv) and omsk hemorrhagic fever (ohfv) viruses are arthropod-borne flaviviruses (family flaviviridae, genus flavivirus). these viruses are quite similar at both the nucleotide and amino acid level, yet they are very divergent in their biological properties and in the diseases they cause. the objective of this study was to examine the putative receptor-binding domains of the flaviviruses, the envelope (e) prot ...200415248774
isolation of capsid protein dimers from the tick-borne encephalitis flavivirus and in vitro assembly of capsid-like particles.flaviviruses have a spherical capsid that is composed of multiple copies of a single capsid protein and, in contrast to the viral envelope, apparently does not have an icosahedral structure. so far, attempts to isolate distinct particulate capsids and soluble forms of the capsid protein from purified virions as well as to assemble capsid-like particles in vitro have been largely unsuccessful. here we describe the isolation of nucleocapsids from tick-borne encephalitis (tbe) virus and their disin ...200415254179
structure and function of the 3' terminal six nucleotides of the west nile virus genome in viral replication.using a self-replicating reporting replicon of west nile (wn) virus, we performed a mutagenesis analysis to define the structure and function of the 3'-terminal 6 nucleotides (nt) (5'-ggaucu(oh)-3') of the wn virus genome in viral replication. we show that mutations of nucleotide sequence or base pair structure of any of the 3'-terminal 6 nt do not significantly affect viral translation, but exert discrete effects on rna replication. (i). the flavivirus-conserved terminal 3' u is optimal for wn ...200415254187
common e protein determinants for attenuation of glycosaminoglycan-binding variants of japanese encephalitis and west nile viruses.natural isolates and laboratory strains of west nile virus (wnv) and japanese encephalitis virus (jev) were attenuated for neuroinvasiveness in mouse models for flavivirus encephalitis by serial passage in human adenocarcinoma (sw13) cells. the passage variants displayed a small-plaque phenotype, augmented affinity for heparin-sepharose, and a marked increase in specific infectivity for sw13 cells relative to the respective parental viruses, while the specific infectivity for vero cells was not ...200415254199
west nile virus infection.the epidemiology, virology, and transmission of west nile virus (wnv) are reviewed, and the clinical features, diagnosis, and treatment of wnv infection are examined.200415259752
action of celgosivir (6 o-butanoyl castanospermine) against the pestivirus bvdv: implications for the treatment of hepatitis c.alpha-glucosidase i inhibitors have been shown to inhibit the replication of a broad range of enveloped viruses by preventing the correct folding of their envelope glycoproteins. this study assesses the potential of 6 o-butanoyl castanospermine (celgosivir) as a treatment for hepatitis c virus (hcv). in the absence of an adequate culture system for hcv, the closely related virus, bovine viral diarrhoea virus (bvdv), was used as a surrogate model. using both a plaque assay and a cytopathic effect ...200415266896
west nile virus vaccines.west nile virus (wnv) is a mosquito-borne flavivirus that is emerging as a global pathogen. in the last decade, virulent strains of the virus have been associated with significant outbreaks of human and animal disease in europe, the middle east and north america. efforts to develop human and veterinary vaccines have taken both traditional and novel approaches. a formalin-inactivated whole virus vaccine has been approved for use in horses. dna vaccines coding for the structural wnv proteins have ...200415268663
flavivirus encephalitis. 200415269317
detection of genome-scale ordered rna structure (gors) in genomes of positive-stranded rna viruses: implications for virus evolution and host persistence.discrete rna secondary and higher-order structures, typically local in extent, play a fundamental role in rna virus replication. using new bioinformatics analysis methods, we have identified genome-scale ordered rna structure (gors) in many genera and families of positive-strand animal and plant rna viruses. there was remarkably variability between genera that possess this characteristic; for example, hepaciviruses in the family flaviviridae show evidence for extensive internal base-pairing thro ...200415273323
pathology and viral distribution in fatal usutu virus infections of birds from the 2001 and 2002 outbreaks in austria.in the summer of 2001, usutu virus (usuv) was isolated for the first time in europe, from an episode of mass mortality in eurasian blackbirds (turdus merula). in the present study, 40 of the birds (representing three species), confirmed as cases of usuv infection, were examined by four methods (histopathology, immunohistochemistry [ihc], in-situ hybridization [ish] and reverse-transcriptase polymerase chain reaction [rt-pcr]). the major macroscopical finding was hepatosplenomegaly; histologicall ...200415276857
modulation of dengue virus infection of dendritic cells by aedes aegypti saliva.dengue virus (dv) is a flavivirus carried by the aedes aegypti mosquito that causes a spectrum of illnesses in the tropics, including dengue fever, dengue hemorrhagic fever, and dengue shock syndrome. dendritic cells (dcs) are professional antigen presenting cells recently shown to be permissive for dv, and implicated as the primary targets of initial dv infection. dv is transmitted to human host by infected mosquitoes during a blood meal, but it is currently unknown whether transmission is modi ...200415279703
effect of membrane curvature-modifying lipids on membrane fusion by tick-borne encephalitis virus.enveloped viruses enter cells by fusion of their own membrane with a cellular membrane. incorporation of inverted-cone-shaped lipids such as lysophosphatidylcholine (lpc) into the outer leaflet of target membranes has been shown previously to impair fusion mediated by class i viral fusion proteins, e.g., the influenza virus hemagglutinin. it has been suggested that these results provide evidence for the stalk-pore model of fusion, which involves a hemifusion intermediate (stalk) with highly bent ...200415280462
[densities of the tick (ixodes ricinus) and coexistence of the louping ill virus and tick borne encephalitis on the island of bornholm]. 200415285165
comparisons of physical separation methods of kunjin virus-induced membranes.the two sets of connected membranes induced in kunjin virus-infected cells are characterized by the presence of ns3 helicase/protease in both, and by rna-dependent rna polymerase (rdrp) activity plus the associated double-stranded rna (dsrna) template in vesicle packets (vp), or by the absence of both the vp-specific markers in the convoluted membranes/paracrystalline arrays (cm/pc). attempts were made to separate flavivirus-induced membranes by sedimentation or flotation analyses in density gra ...200415288961
arguments for live flavivirus vaccines. 200415302184
arguments for live flavivirus vaccines. 200415302187
arguments for live flavivirus vaccines. 200415302188
fusion pcr generated japanese encephalitis virus/dengue 4 virus chimera exhibits lack of neuroinvasiveness, attenuated neurovirulence, and a dual-flavi immune response in mice.the first flavivirus chimera encoding dengue 4 virus (d4) prm and e structural proteins in a japanese encephalitis virus (jev) backbone was successfully generated using the long-pcr based cdna-fragment stitching (lpcrcfs) technique, demonstrating the technique's applicability for rapid preparation of flavivirus chimeras. the jev/d4 chimera multiplied at levels equal to jev and d4 in the mosquito cell line c6/36, while in a mouse neuronal cell line (n2a) jev replicated efficiently, but jev/d4 and ...200415302944
Displaying items 1701 - 1800 of 3318